Curtain wall assemblies, large expanses of aluminum framing, are not traditionally known for their thermal efficiency. While insulated spandrels within the curtain wall framing have been used in an attempt to improve the thermal performance of the curtain wall system, research and testing has shown that typical insulated backpan systems fall short of expectations for the thermal resistance of opaque walls in many codes and standards.
Attic ventilation is a firmly established requirement for residential wood-framed buildings. Attic ventilation is cited to be a benefit for moisture control, reducing cooling loads in hot climates, minimizing ice dams in cold climates, and extending the service life of roof materials by reducing surface temperatures. There is an ongoing debate on the real significance of some of these benefits and mandatory venting requirements.
As codes and standards evolve towards low or net-zero energy buildings, the practicality of achieving these targets in high-rise concrete construction gets increasingly challenging. High-rise residential buildings are becoming more common as cities redevelop and add density. Current design and construction practice for high-rise multi-unit residential buildings (MURBs) presents a number of constraints with regards to achieving high levels of energy performance.
Building envelope thermal performance is greatly affected by thermal bridging, or localized areas of increased heat flow through walls and roofs. Mitigating the impact of thermal bridging is not only necessary to reduce energy consumption but is also an important consideration for minimizing the risk of condensation on cold surfaces and for maintaining occupant comfort.
Across North America we are seeing more stringent thermal requirements in building codes and designers are responding by increasing the amount of insulation in walls, all in an attempt to increase energy efficiency in buildings. But how effective are these changes on building energy use when we ignore the impacts of 3-dimensional heat flow in transition building components, like exposed concrete slabs, window flashings and un-insulated parapets. What if these building components we neglect have a much greater impact on energy than we realize? And how will that affect the decisions we currently make on the building envelope?